Electronic power supplies are commonly used. There are occasions where it is necessary to adjust some of the working parameters of the power supply such as the output voltage, the supplied current and so on. This is commonly done by applying an analog input signal to the analog input of an adjustable power supply module. For example, an adjustable power supply module capable of supplying voltage up to 100 V will produce its maximum voltage when applying 10 Volts to its analog input while application of 5 volts to the analog input will cause the power supply module to produce only 50 Volts.
Several standards are used to form the relation between the control input signals and the power supply operation, for example: the signal corresponding to the supply maximum voltage, the analog signal may be applied in the form of current instead of voltage or the analog input signal may be the application of specific resistance between input terminals of the power supply module.
In addition, some power supply modules are equipped with analog monitoring output or outputs for monitoring their operation. For example, it may be useful to monitor the current or the power drawn by the load. A monitoring analog output producing an analog output signal of a voltage proportional to the current drawn by the load, may be connected to a display unit for displaying and monitoring the supplied current.
In order to properly adjust and correctly monitor the operation of the adjustable power supply unit, it is necessary to provide it with the correct analog input signals and to be able to translate the analog monitoring output signal for meaningful interpretation of the power supply working parameters. Since several standards and proprietary translation methods are used in the industry, hardware alterations are needed to set up a power supply module for its specific use. Setting up may be done at manufacturing by soldering in components (usually resistors) of specific values, or in the field by configuring the system using switches and jumpers to select the desired value among several preinstalled components. These methods limit the flexibly of the system, are time consuming and necessitate manual handling of the system which may be hazardous when done by untrained user.
For example; Xantrex Technology manufactures the XPR series of analog-controlled power supplies for applications including burn-in, electroplating, battery charging, and steering magnets.
Analog control comes standard with the XPR Series for resistive or voltage programming of the output voltage and current limits.
Several models are available with voltage ranges of 0-3 V up to 0-30 KV and maximum current of 1 A up to 60 KA.
Standards used for analog inputs are set at the factory and selected among: Voltage input of 0-5 V or 0-10 V for full range of the supply output, Resistance input of 0-5 k or 0-10 k for full range of the supply output.
Analog monitoring signal proportional to the actual output voltage and current of the power supply is provided using one of two factory-defined standard of 0-5 V or 0-10 V for full range.
It is clear that a user analog input signal may produce undesirable output if the wrong signaling standard is used.
The Series has a straightforward front panel, featuring a seven segment LED display with several status and alarm indicators, and 10-turn knobs for voltage and current control. The front panel buttons allow users to conveniently set and view the over voltage protection set points, view the output voltage and current limits, enable output shutdown, and offer the flexibility of toggling control of the power supply between the front panel and remote analog control.